posted by ja'Sae .
A shop sells one-pound bags of peanuts for $2 and three-pound bags of peanuts for $5.
If 9 bags are purchased for a total cost of $36, how many three-pound bags were
O + T = 9
T = 9 - O
2O + 5T = 36
Substitute 9-O for T in last equation and solve for O. Insert that value into the first equation and solve for T. Check by inserting both values into the second equation.